Road construction.



F. F. WILLIAMSON dz 1). BRENNAN, JR.

3021) comsmnonon. APPLICATION FILED MAY 2, 1908.

I Patented Jan. 12, 1909.,

2 SHEETS-SHEET 1.

' WITNESS VE/VTDR @0606 mid/b16444 )r 3) ATTORNEYS P. F. WILLIAMSON & D. BRENNAN, JR.

' ROAD CONSTRUCTION.

APPLICATION FILED MAY 2, 19084 Patented Jan. 12, 1909.

' z SHEBTSSHEET 2 UNITED STATES PATENT OFFICE. FREDERICK F. VILLIAMSON AND fiANIELIB RENl IAN, J'R., OF NEW YORK, N. Y., ASSlGNORS TO SIOILIAN ASPHALT PAVING QO., OF NElV YORK, N. Y., A CORPORATION OF NEW YORK.

ROAD coNs'rBUe'rIoN.

with a smooth, durable, semi-e astic, dustless and non-slip )ery Wearin surface. For this purpose we tion involvin the use of stone and asphalt arranged and compacted in an improved manner, as we shall now proceed to describe.

Reference is to be had to the accompanying drawings in which Figure 1 is partly a' cross-section and partly a perspective View (with parts renioyed), illustrating the construction of our improved road; Fig. 2 is a partial elevation of a roller employed by us in making such road; and Fig. 3 is a top View of another form of roller.

On a proper road bed A we spread, loosely, enough clean broken stone B of asubstantial and uniform size to make a finished layer able to support the weight of the traflic. For this we prefer hard and tough stone, such as trap rock, of a size which would pass through ,a two and a quarter inch (2%") ring and free from all pieces small enou h to go through an inch and an eighth (1% ring. For softer and more friable stones we prefer a size larger, say 21- rejecting 1 to 3", rejecting 1. On a ood road bed a layer of loose stone 6 inches thick, rolled down to about 4 inches thick is usually sufficicnt. The loose bed of stones will have about of voids and the finished layer about 12% of voids. We roll this loose, unpacked layer of clean stones with a heavy roller (an ordinary self-propelled roller of about tons weight will do, or by means of a grooved roller such as referred to hereinafter), adding as the rolling progresses,

fresh, clean stones of the same quality and size to work into and thicken, the layer if necessary, and in like manner, and by further rolling, we fill all depressions and remove surplus stones from high places. until the Specification of Lettera Patent. Application filed. may 2, 1908. Serial No. 136,463.

ave devised a novel construe- Patented. 'J'an. 12, 1909.

surface of the layer is brought to the required grade and refuses to 0 any lower. (It is well understood that in t is layer B we do not use any fine stuff that would act as a binder.) The stones being clear .of binding material or fillerofany kind, do not remain but are forced by the action of the re upon and between each other. The smaller stones and pieces broken off by the pressure and movement of the roller find their way to the bottom, while the good sized strong alinement; and though the stones in the layer 4 in their accidental relative positions as spread,

I ler to findtheir bestbearings'upon the road bed and are not as yet in any sense bound to ether,

they lie closer and have a stronger an more efl'ective bearing upon and between one an other, than if a binder of anykind, or a mixture with finely crushed stones, grit, gravel, sand or earths were used, or if a mixture of asphalt or any fine stuff were present. The rolling operation therefore securely anchors or bonds the stones of the lower layer.

\ Care being taken to keep this compact layer Bof clean stones and its alined surface intact as finished by the roller, We flood it with enough soft asphalt, heated to a liquid'consistenc to fill all the voids and interstices,

in the 'ayer and at the same time to overflow and fills to overflowing the voids inv the.

layer B, but the stones comprising the layer. being all of good size, especially at the surface, the asphalt does not in the least dis-- turb the solid bearingsthey have u on and between one another, as brought '21 out by the movement and pressure of the roller.

The asphalt we use is preferably of the best quality,-as tough and soft as it can be made, without liquefying injuriously in hot weather. It can be made from various bituminous ingredients to suit our requirements by those skilled in the art. Generally speaking, an asphalt that will begin to melt at about 100 Fahrenheit, and will completely liquefy'at about 300 Fahrenheit, is stiff enough for our purpose.

The melting and liquefying points of the soft asphalt are greatly modified (as far as the heat of the Weather is concerned) by the presence of the stones therein.- The as phalt is a very slow conductor of heat or cold and the stones embedded in it will take a long time to heat in response to weather conditions and as the asphalt itself will cling fast and not liquefy until the stones buried in it are at the same temperature that will liquefy the asphalt, the heat of the day is passed long before. this temperature is reached and the mass has time-to cool off and when 1t is properly proportioned as to again and resumethe normal or average temperature \vhich is not injurious to the road. 'e now apply the stone for the wearing coat C of the road, consisting, -1'1sually, of a mixture of small stones and grit, as made by thecrusher and screened out of the stones used for the under layer generally called coarse screenings). If this material comes in two grades, generally known 'as 5f stone and fine screenings the screenings or grit may be spread on first and the l stone spread on top of it). This material we spread evenly oyer the bed of soft asphalt left for it upon the surface of the under layer, taking care 35 that it is well mixed and not all fine in one place and all coarse in another. The s n-ending is best done by hand on the spot from a heap ,on a so-called mixing board by expert spreaders who, with'shovels, can mix and apply it with a surprising regularity of vmixtur'and quantity. l For hard and ,tough coarse screeningsof trap rock there would be spread upon a half-inch bed of asphalt enough to make a finished surface layer 1-} inch thick including the asphalt. This will take unpacked screenings about 1% inch thick. A thicker bed of asphalt will take more screenings in proportion. If the screeningsare fromrock of a friable nature they should be coarser in the first instance, as they will wear and cut down to a smaller size by the process of as sortment and packing into place, used in finishing the road, as hereinafter described. The coat of screenings will sink into and cover the bed of soft asphalt, making a rough surface which is then rolled and fin ished by a special roller as hereinafter described. Ve now use aspecial roller (Fig. 9 or Fig. 8 designed by us for the above purpose, and described hereinafter) t0 knead the screenings into the asphaltand at the same tin1e"to' classify the "screenings by forcing the good sized strong pieces of stone w; Ilherein to collect at the. nr'face and smaller pieces and grit "assemble in lower der layer and into thechinksthereof. The top coat is thus graded in den'sity, bein nearly all stone at the surface; (of the road and nearly all asphalt in the chinks of the .under layer, there being a lesser proportion of stone or-grit and more asphalt as the distance from the surface increases. We use a stifi'er asphalt and a larger proportion of-fine grit or dustin the surface layer on steep hills facing the sun than we do on level ground and in shady places. We would use a stiller asphalt in the South ern States than in or the Northwest, for example.

In the construction illustrated by Fig. 2, the roller D We use number of ribs or annular ridges D"thereon Weight and as to number, shape and dimensionsof the ridges and of the spaces between and is used by running it backward and for- Ward and in every direction upon thescreeningsand ashphalt, it Will rapidly knead the stones into the asphalt and at the same time grade them and thereby vary the proportion of asphalt and "screenings Within the top layer as above described. To be durable and to be easily cleaned the roller should have inclined faces on the side of its-ribs or ridges. face of a rib should be about one-third of the interval between said surface,'or in other Words theaggregate width of these surfaces should be about one-fourth of the rollers length. In order-that the under layer may etween said ribs should not be over about one-half of the thickness of. the finished layer C.

and of the upper layer,.,we secure an improved result by reason of the fact that the rolling operation brings about what may be called a classification of the material, that is, the larger stones are brought into the surface, while smaller ones seek lower levels. This beneficial action for our purpose may be explained as follows: If there is not too much binder present, and if the stones are clean'as in layer B, the roller at first pushes a Wave of loose stones ahead of it involving a movement among the stones which has a screening efi'ectf allowing the small stones the coarser stones are to that then as the pressure of the on'theedge of a sto n e,- that whereby also extent raised roller comes to its size and-smaller pieces get an the stones afe s'oon graded thee-larger ones e layer-easfl i wea s F am afim'sh positions in the asphalt reaching to the un- New England, Canada,

for this purpose has a.

The width of the cylindrical surstone is tilted up to an extent in proportion er the tilted endj By a repetition of-this action-- being forced to: collect at th i SL TfQCe of the" l not be disturbed the depth of the grooves Both-in rolling "the stone of the layer B I 0 to go to the bottom of the mass by gravity,

first comparatively coarse layer of stones;

but to classify the screenings in the surface layer G and in the presence of the asphalt requiresa different and a more efi'ective maclune,- so we provide therefora number of narrow rollers, or disks, as it were, spaced apart, the rolling face of each disk having of course two edges. A disk roller, as we may call it, as designed for our purpose, of the same weight and general dimensions as a plain'rollcr, would be composed for instance of 16' disks having 32 angular edges, the aggregate rolling faces of the disk having 4- times the pressure on the road of a plain roller of the same size and weight.

A tilting effect of the edges of a ridge or ring on the stones in the layer is manifestly much greater than can be produced by the rolling faces thereof, as after the stone is tilted up the roller passes by and gives time for small stuff to get under the tilted up end and very often forces smaller pieces under such'raiscd end by reaction. This kind of a roller will not push so much of a wave in front of it as a flat roller does, but induces a complexity of movements in the mass whereby the stones soon become classified and find their best fitting places in the layer, the larger ones onitop,'thus with this form of roller the resistance of the soft asphalt to the classification of the stones into position is overcome anditv progresses rapidly to comi ne/edges or ridges of the roller cut into the mass at first to the full depth thereof, but at each succeeding time of going over they cut in less and less, and finally do not cut in at all, leaving the surface smooth with the best stones face up as described. The inclined faces D adjacent to each of said edges or ridges, assist in crowding the stones sidewise so as to facilitate their rearrangement and classification. The rolling taking place on a comparatively thin layer superposed on a firmly established alined surface of large stones, assists in the operation as also does a peculiar pumping action of the asphalt itself which begins almost immedi ately and is retained during the life of the rod.

The machine of which the grooved roller forms the working part may be a self-propelled one of usual character. Its steeringroll may be plain and not grooved, so that it will flatten out the grooves made at first by the main roller. e prefer to provide means whereby the surface of the roller may be i eptglean. (shave illustrated'such means in conjunction with a somewhat different form.- ofour roller shown in Fig. 3, which is characterized by the employment of spiral ribs D" in lieu ofthe annular ribs of Fig-. 2: The cleaning device in this case consists of a chain E suitably carried by the. frame of the roller, the links of said chain being so formed as to conform to the outline of the ribs D Of course as the roller rotates the chain will be moved slowly and the grooves between the spiral ribs as well as the faces of said ribs will be kept clean. With a roller having annular ribs as in Fig. 2 a simple toothed bar secured to the frame in such a. way that its teeth would roject between the ribs of the roller won (1 be suflicient.- The spirally ribbed roller of'in g. 3 has the advantage of a tendency to crowd the covering of the road toward'the center, which is of assistance in giving the road the proper transverse form with the center of the road higher than the sides. Of course it is understoodthatto accomplish this result the roller would be made to travel on one side of the road going in one direction and on the other side coming back.

The surface of the road when rolled as described is composed of a coherent layer of stones with alined surfaces each stone being:

surrounded and held conjointly. with its neighbors by a thin skin of asphalt. This crust-like surface has beneath it the smaller stones and vgrit, having proportionately more and more asphalt in it as the surface of the under layer is reached, the gritty mixture extending more or less into the crevices ofthe underlayer; the asphalt on the lower interstices of the under layer has little or no grit therein.

Thev connection and extension of the iden tical asphaltthrough and into both layers prevent the surface layer from being stripped off by Elie suction of) heavy and fast automobile trafiic. The surface layer. is always elastic. has little or no supporting re sistance to the tralfio, depending for this en tirely on the under layer. We desire to call particular attention to the fact that the stones in the lower layer B are in supporting engagement with each other, so that the weight of the traiiic is borne by these stones and does not rest at all, or atleast not materially upon the asphalt contained in said layer. 7

The coherent surface forms and acts as a sort of diaphragm and sets up a compression and pumping action from the vibration of the traflic that exerts as a capillary suction clear down as far as the asphalt goes.

The wear of the-surface is remarkably small, as the stones comprising it are cushioned by the asphalt, not being directly between the wheels and the hard supporting surface as in the ordinary niacadam road. The wear and tl'ie'usualstreetdirt areiust.

' about sufficient to keep the surface from be working it in with the special grooved roller By our system we can use the size of stone usually made by crushers and we can proportion the thickness and size of the stone in the two layers and the amount of asphalt needed in such a way as to use the whole product of a crusher from the maximum suitable size down.

By our syst'eYn old macadamized roads can be resurfaced using the broken stone and screenings already in the road, the necessary asphalt only being added. Gravel will do for our surface layer and is often cheaper and better for the surface than screenings made from' the country rock. VVhen the asphalt cools, the stones in the under layer B are held in their strongest and most elfective position to support the weight of the trallic and this stren th will be more uniform throughout the ayer because of the comparative uniformity of the size of the stone in the layer, it being nearly impossible to get an even consistency with a mixture containing fine stufi'in such a layer. We can, howsw'er, ,get very good results in the layer E from any .stronggood sized broken stone that is clean and free'from a detrimental proportion of chips and fines such as would prevent classification by the roller thou h care must be taken about this as any boun spots in the 1 under layer-would causethe Stripping olf of theupper layer by heavy automobile trafiic.

Small bonded or unclassified spots in the layer, however, can be to a certain extent,

repaired, as it were, by hand with a heavy 'rammer before pouring theasphalt.

' donot want to be confined too closely,

- as thererare many schemes of repair if the laying.

under layer is not well classified. It can be harrowed and then rolled, for instance so the top of the layer would be clean anyway, which though not as good as a layer clean all through, would be admissible sometimes when the question of cost is a-controlling one.

Our system does not re'qu'ire expensive apparatus for asserting the stones and for heating and mixing them with the asphalt before We force the best assortment of the stones for our purpose, as they lie in the road, 'by our rolling system and we'getthe bestuse, of the asphalt constituent of the road by a 's'ingleoperation, also in place.

' 'Itwill be. seen that our road consists, suby .stantially-,-Tif,two layers of stone, an under layer 'o f coarse stones'and an upper layer of smaller stones forming with soft asphalt the wearing surface of the road; that both layers applied in a single operation without pre- -vious mixing with the stones of either layer,

but that by previous-rolling a still and firm. under layer 15 produced while an elastic surface layer is obtainedby putting the asphalt in place first, then applying the'stones and rolling them into it to lorhl a surface more or less elastic according to the proportion of stones in the layer. 'lhe non elastic base preserves the grade and crown oftne surIace layer, which is anchored Iast to the under layer by the identical asphalt extending through. both layers. y

W e claim as our invention:

1. in a road or the line, an under layer of comparatively large SLUlleS in supporting contact andset close together at the top of the layer parallel with the contour or the finished road, and an upper-layer of smaller stones, the spaces between the stones of both layers and between the layers being filled with a soft-bituminous binuer of identical quality extending within both layers, the stones in each-layer'belng classified. so that thelarger stones are near the-top.

2. In a road or the like an under layer of coarse stones and an upper layer of smaller stones, the spaces between the stones of both layers and between the layers being filled with a soft bituminous binder of identical quality, the larger stones in each layer being at the top, face up, close together and parallel' with the contour of the road.

3. In a road or the like, an under layer of coarse stones and an upper layer of smaller stones, the spaces between the stones of both layers and between the layers being filled with a soft bituminous binder of identical quality, the larger stones in the lower layer relatively large stones with the largest stones at the .top and a soft bituminous binder stones with the larger stones on'top, then pouring a bituminous binder into the voids of the said under layer and over the top thereof, adding smaller stones to the bituminous binder on topto form an upper or surface layer, and rolling this upper or surface layer.

6. The herein described improvement in the construction of roads and the like, which consists in forming-an under layer of rela tive y large stones, rolling said layer t bring about a classification or grading- 0 stones with the larger stones on top, then pouring a bituminous binder into the voids of said under layer and over the .top thereof, adding smaller stones to 'the bituminous binder on top to form an upper or surface layer, and rolling this upper or surface layer with a grooved roller to Work the larger stones of said layer into the bituminous binder and the smaller ones bottom.

7. The herein described improvement in the construction of roads and the like, Whichconsists in forming "a layer exclusively of stones, rolling said layer together to coinpact it and to securely pack the' stones together and then pouring a bituminous binder into the voids of the packed layer.

8. The herein describedimprovement in the'construction of roads and the like, which consists in. forming an under layer exclu-' sively of relatively large stones, rolling said layer to compact it,jthen pouring a bltum b nous binder into the voids of'said under upon thelappli cation of Frederick record of the case in the Patent Ofii Signed. and sealed this 9th day of.

y [SEAL.]

Correction in Letters P No. 909,499.

toward the It is hereby certified that in Letters Patent No. 90

I Williamson and Daniel Brennan, J12, of New Xork, N. Y., for an improyement in printed specification requiring; correction, as follows: bituminous binder should be inclosed by a paren Patent should be'read with this correction therein that layer and over the top thereof and adding sI naller stones on top to form an upper or surface layer. 7

9. In a road or the like, a layer consisting of stones packed and bonded by roller pres sure exerted on the stones alone and having the voids intervening between them filled With a bituminous binder.

' FREDERICK F. WILLIAMSON.

TMNIEL BRENNAN, JR.

Witnesses:

JOHN Lo'rKA, JOHN A. KnnLnxBEcK.

February, A. D., 1909 p G. G. BILLING Acting Commissioner of Patents.

10. In a road or the like, an under layer 9399, granted January 12, 1509 Road Construction, an error appears in the In line 91, page 1, the words thesis; and that the said Letters the same may conform to the consists in forming-an under layer of rela tive y large stones, rolling said layer t bring about a classification or grading- 0 stones with the larger stones on top, then pouring a bituminous binder into the voids of said under layer and over the .top thereof, adding smaller stones to 'the bituminous binder on top to form an upper or surface layer, and rolling this upper or surface layer with a grooved roller to Work the larger stones of said layer into the bituminous binder and the smaller ones bottom.

7. The herein described improvement in the construction of roads and the like, Whichconsists in forming "a layer exclusively of stones, rolling said layer together to coinpact it and to securely pack the' stones together and then pouring a bituminous binder into the voids of the packed layer.

8. The herein describedimprovement in the'construction of roads and the like, which consists in. forming an under layer exclu-' sively of relatively large stones, rolling said layer to compact it,jthen pouring a bltum b nous binder into the voids of'said under upon thelappli cation of Frederick record of the case in the Patent Ofii Signed. and sealed this 9th day of.

y [SEAL.]

Correction in Letters P No. 909,499.

toward the It is hereby certified that in Letters Patent No. 90

I Williamson and Daniel Brennan, J12, of New Xork, N. Y., for an improyement in printed specification requiring; correction, as follows: bituminous binder should be inclosed by a paren Patent should be'read with this correction therein that layer and over the top thereof and adding sI naller stones on top to form an upper or surface layer. 7

9. In a road or the like, a layer consisting of stones packed and bonded by roller pres sure exerted on the stones alone and having the voids intervening between them filled With a bituminous binder.

' FREDERICK F. WILLIAMSON.

TMNIEL BRENNAN, JR.

Witnesses:

JOHN Lo'rKA, JOHN A. KnnLnxBEcK.

February, A. D., 1909 p G. G. BILLING Acting Commissioner of Patents.

10. In a road or the like, an under layer 9399, granted January 12, 1509 Road Construction, an error appears in the In line 91, page 1, the words thesis; and that the said Letters the same may conform to the Correction in Letters Patent No. 909.499

It is hereby certified that in Letters, Patent No. .lOfh-lfif. r:m:m1 Jrunmry 112, Ifiir.

upon the application 01' Fredvrk-k F. Williamson and Dunk] [In-Luau. .51", 0f Ak-w York N. Y. for an im mrovunmnt in Road (enstnn-Linrfl' a: w; 4' c! mum in :W J,

printer specific-111mm requiring: corrwiion, as follows: In 1:11. u. ":w axi:

hitzmuhmm binder should being-1mm! by a parenthesis; and that Hm said lmm-w Ptil'llh |1uuld he read with this um'rvniiou Hwruin ihm Um 9mm 1:1.15' vvni mm m {51rl'ecord of the (use in the PkLh'llt ()flutie.

Sfiuvd and swim] 1m 9th day of' February, A. 1).. Mint [slink] (I 1, HIIJ'AJN H 

